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Updated: Jun 11, 2025
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Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars
Published on: February 11, 2020
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Enhancing Resistance to Wetting Transition through the Concave Structures.
Jinhoon Lee1, Jinwoo Park1, Kwang Hui Jung1
1Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Republic of Korea.
Advanced Materials (Deerfield Beach, Fla.)
|October 3, 2024
Summary
A novel concave pillar design enhances superhydrophobic surface stability against water droplet impacts and hydrostatic pressure. This bio-inspired approach prevents the Cassie-Baxter to Wenzel transition, enabling robust water repellency.
Area of Science:
- Materials Science
- Surface Science
- Tribology
Background:
- Superhydrophobic surfaces mimic natural water-repellent structures.
- Achieving stable superhydrophobicity requires overcoming transitions like Cassie-Baxter to Wenzel (CWT).
- Existing designs often use hierarchical or reentrant structures to prevent CWT.
Purpose of the Study:
- To introduce and evaluate a new concave pillar design for stable superhydrophobic surfaces.
- To assess the thermodynamic and kinetic stability of concave pillars under various conditions.
- To compare the performance of concave pillars against standard normal pillars.
Main Methods:
- Investigated thermodynamic and kinetic stabilities of concave pillars.
- Subjected surfaces to continuous hydrostatic pressure and sudden water droplet impacts (Weber numbers).
- Compared concave pillars to standard superhydrophobic normal pillars.
Main Results:
- Concave pillars demonstrated enhanced impact resistance, preventing CWT up to a critical Weber number of ~27.6 (1.6x higher than normal pillars).
- Underwater air film (plastron) stability was improved due to convex air caps in concave cavities.
- Downward Laplace pressure from air caps counteracted hydrostatic pressure, hindering air diffusion.
Conclusions:
- Concave pillar design offers a pioneering strategy for stable superhydrophobic surfaces.
- Trapped air caps in concave structures significantly contribute to maintaining the Cassie-Baxter state.
- This approach facilitates the exploration and practical application of robust superhydrophobic materials.
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